The U.S. Nuclear Regulatory Commission (NRC) is amending its spent fuel storage regulations by revising the Holtec International HI- STORM Flood/Wind Multipurpose Canister Storage System listing within the "List of approved spent fuel storage casks" to include Amendment No. 5 to Certificate of Compliance No. 1032. Amendment No. 5 revises the certificate of compliance to: Add new heat load patterns and revise the minimum required cooling time for two multipurpose canisters MPC-89 and MPC-37; add new fuel types to the approved contents; allow an exception to a code to permit use of certain duplex stainless steels; use an analysis model to revise the calculation for evaluating effective fuel conductivities; add the use of the damaged fuel isolator; add two versions of the standard variable weight transfer cask; add the option of using cyclic vacuum drying; and make changes to the final safety analysis report to add new types of fuel assemblies, add a definition to it and to the certificate of compliance, and add the required shielding evaluation to Section 5.4.8. In addition, Amendment No. 5 makes several clarifications and minor changes. These changes are discussed in more detail in the "Discussion of Changes" section of this direct final rule.